Mixing rotor for plastic gun

ABSTRACT

In a gun of the spray gun type for mixing and applying a twopart mixture, such as a plastic and its catalyst, having a mixing chamber that receives at one end thereof controlled or metered amounts of the two ingredients of the mixture from their respective sources of supply and discharges the mixture from an outlet at the other end, the improvement comprising a mixing rotor, with mixing blades extending radially from a central body. The rotor is mounted in the chamber and is rotated continuously while the gun is in use. The upstream sides of the rotor blades are inclined relative to their respective planes of rotation to exert an axial flow impeller type action on the contents of the chamber thereby creating a high degree of turbulence within the chamber that tends to propel the contents back away from the chamber outlet.

nite States Patet [72] Inventor John H. Eberle El Cajon, Calif. [21] App1.N0. 833,617 [22] Filed June 16, 1969 [45] Patented Nov. 23, 1971 [73] Assignee Eberle Enterprises San Diego, Calif.

[54] MIXING ROTOR FOR PLASTIC GUN 7 Claims, 2 Drawing Figs.

[52] U.S, Cl 259/7, 259/42, 239/142. 239/399, 416/198 [51] int. Cl B01f7/04 [50] Field of Search 239/142, 399, 589, 601; 259/7.10, 16, 22, 41, 33, 65,106; 416/198, 200

[56] References Cited UNITED STATES PATENTS 2,997,968 8/1961 Fitzpatrick et a1 259/10 X 3,035,775 5/1962 Edwards et al. 239/142 3,088,712 5/1963 Snow et al. 259/7 3,123,306 3/1964 Bradley 239/142 3,304,010 2/1967 Cantrell et al. 239/142 3,417,923 12/1968 Carlson 239/142 X Primary Examiner-Walter A. Scheel Assistant Examiner-Alan l. Cantor Attorney-Carl R. Brown ABSTRACT: In a gun of the spray gun type for mixing and applying a two-part mixture, such as a plastic and its catalyst, having a mixing chamber that receives at one end thereof controlled or metered amounts of the two ingredients of the mixture from their respective sources of supply and discharges the mixture from an outlet at the other end, the improvement comprising a mixing rotor, with mixing blades extending radially from a central body. The rotor is mounted in the chamber and is rotated continuously while the gun is in use. The up stream sides of the rotor blades are inclined relative to their respective planes of rotation to exert an axial flow impeller type action on the contents of the chamber thereby creating a high degree of turbulence within the chamber that tends to propel the contents back away from the chamber outlet.

PATENTEDuuv 23 I971 INVENTOR JOHN H. EBERLE BY M ATTORNEY MIXING ROTOR FOR PLASTIC GUN BACKGROUND OF THE INVENTION An important use of epoxy resin as an adhesive is that of attaching traffic markers to highway and city pavements. These markers are made in numerous styles, some of which are domed plastic disks that may be several inches in diameter and a half or three-quarters of an inch in height. These markers are attached to the pavement in rows in place of the well-known painted traffic markers strips. A presently preferred method of attaching these and other generally similar traffic markers is to apply a dab of catalyzed epoxy resin in the desired spot and then press the marker down onto the resin, thus securing the marker in position. A preferred method of apply the catalyzed plastic to the pavement is by means of a well-known type of two ingredient mixing gun, with hoses leading into the gun from separate pressurized supplies of plastic and catalyst. Separate passages in the gun conduct controlled amounts of the ingredients from their respective hoses into a mixing chamber, wherein the two ingredients are intermixed by a rotor having radial blades extending therefrom. The mixing rotor is driven by an air motor on the gun and the mixture is discharged from the mixing chamber through a discharge outlet located axially beyond the mixing rotor in the direction of plastic flow. Compressed air for driving the motor is provided by a usual high-pressure airhose, and a supply of pressurized cleaning solvent is provided through an additional hose communicating with the mixing chamber.

While the mixing guns presently used supply the premixed plastic, they often do not provide as thorough an intermixing of the ingredients as desired. Also such known guns have an undesirable feature in that between operations when the gun is held in discharge-end-down position, drops of the premixed plastic are allowed to dribble out onto the pavement. At the end of a period of use, a mixture of catalyzed plastic remains in the mixing chamber, of the known guns, and it is necessary that this mixture be removed or it will harden and prevent further use of the gun. Such removal is accomplished by flushing the chamber with a suitable solvent, such as acetone, from the supply thereof communicating with the mixing chamber, while driving the rotor by means of the air motor. However, in existing mixing gun designs, the cleaning of the chamber through the flushing action is sometimes incomplete, causing difficulties in further use of the gun after a time interval of nonuse.

SUMMARY OF THE INVENTION A primary object of the present invention is to provide an improved, dribble-preventing mixing rotor for a gun used in the application of premixed, two-ingredient, plastic material by shaping the radial blades of a rotor mounted in a mixing chamber so as to retain the contents within the chamber except during periods of plastic discharge. Another object of the invention is to induce an axial flow impeller type action within the mixing chamber to increase turbulence within the chamber and thereby more thoroughly mix the ingredients therein.

The foregoing objectives and advantages of the invention will be apparent from the following description and the accompanying drawings, wherein:

FIG. 1 is a side elevational view ofa plastic gun embodying the invention, portions being broken away.

FIG. 2 is an enlarged, perspective view of the mixing rotor of the gun shown in FIG. 1, a portion of its mounting shaft being shown.

Referring to the drawings in detail, a two-ingredient gun of a wellknown type comprises a body with the usual handgrip 11 and actuating trigger 12. A high-pressure air hose 13 is connected to the lower end of the handgrip 11 and communicates with a suitable supply of compressed air, not shown. Two hoses 14a and 14b are connected to side by side input connections in the bottom of the gun, only one of the input connections is visible in the drawing. One of the hoses is connected to a supply of pressurized plastic, for example, epoxy resin, and the other hose is connected to a supply of a suitable catalyst. A hose 15 is also connected from the gun to a pressurized supply of cleaning solvent, such as acetone.

The plastic supply hoses 14a and 14b communicate through passages 17 and 20 in the gun body with the inlet end of a mixing chamber 18, the tubular housing 16 of which is secured in sealed relation on the discharge end of the gun body 10 by a ring nut 19. A discharge nozzle 21 is screwed coaxially onto the threaded discharge end of the mixing chamber housing 16, and has an axial outlet 22 therein. The outlet 22 is threaded to permit the attachment of accessories when the gun used for other purposes, but for handling the viscous plastic material used for attaching pavement markers, the outlet 22 is usually left open as shown in FIG. 1.

A mixing rotor 23 is mounted coaxially within the mixing chamber 18 on a shaft 24, which is joumaled in usual bearings provided for it in the gun body. The shaft 24 extends all the way through the gun body and is connected coaxially to the drive shaft of an air motor 25, which is mounted on the opposite end of the gun body from the mixing chamber 18. The air motor is driven by compressed air supplied through the airhose 13 which air passes through usual trigger-value-controlled passages, not shown, in the gun body 10 and a valvecontrolled air hose 26 connected to the gun body 10 and the air motor 25 by usual fittings.

The mixing rotor 23 comprises an axial body portion 27 having an axial opening therein in which the shaft 24 is secured and a plurality of radially extending blades 28 The blades 28 are of a length from their common axis of rotation that extends just short of the internal surface of the cylindrical mixing chamber 18. The blades 28 are arranged in oppositely extending pairs, each successive pair being offset axially from the next, and rotatively by an angle of degrees.

To provide greater turbulence in the mixing chamber 18 and to prevent dribble of the contents of the mixing chamber 18 from the outlet 22 between successive discharging operations of the gun the upstream sides 29 of the blades 28 comprise planar surfaces that are beveled or inclined, relative to their respective planes of rotation, in a direction which will tend to propel the contents of the mixing chamber 18 back away from the outlet 22. The blades 28, which sweep the chamber 18 closely adjacent the outlet 22 and maintain an equal spacing from that end of the chamber across their entire radial extend, have their upstream faces 29a at the steepest angle of inclination, while the inclined faces of other pairs of blades more remote from the outlet are at lesser angles of inclination relative to their respective planes of rotation. This construction tends to provide the strongest axial propulsive effect on the contents of the mixing chamber adjacent the outlet and thus provides for effective retention of the contents within the chamber, even with the gun held in outlet down position.

OPERATION In using the gun with the improved mixing rotor 23, the gun is operated in a conventional and well-known manner. The air motor 25 is arranged to drive the mixing rotor 23 at a higher speed during periods of plastic discharge, and at a slower speed during the interim therebetween. During periods of plastic discharge, resin and catalyst are forced at suitable pressures through their respective hoses 14a and [4b and passages 17 and 20, into and through the mixing chamber 18 and out the outlet 22. At the same time the inclined faces 29 of the rotor blades improve the mixing effect of the rotor on the contents of the mixing chamber 18 since they produce an axial counterthrust on such contents, which combined with their rotative stirring action, causes extreme turbulence within the mixing chamber.

More importantly however, during interim periods of nondischarge, when the flow of resin and catalyst to the mixing chamber 18 is cut off and the air motor 25 continues to rotate the mixing rotor 23 at a suitable slower speed, the inclined faces 29 of the mixing blades 28 of the rotor produce an axial thrust on the contents of the mixing chamber, tending to propel such contents away from the outlet 22. Since the chamber is closed at its inlet end, no actual flow of the chamber contents is possible. However, the action is sufficient to hold the contents in the chamber even though the chamber and outlet 22 are pointed downward, preventing dribbling of the contents from the mixing chamber during the interim periods of nondischarge.

After each period of use, it is essential and common practice to thoroughly clean the gun of the catalyzed plastic. This is accomplished by shutting off the flow of plastic and catalyst to the mixing chamber through the hoses 14a and 14b and supplying a suitable pressurized cleaning solvent, such as acetone, to the chamber 18 through the hose 15. With the acetone in the chamber 18, the rotor 23 is rotatively driven to create an extreme turbulence and flushing of the mixed plastic and catalyst from the mixing chamber 18. The rotor 23 tends to drive the acetone fluid axially inward flushing the mixed plastic and catalyst from the chamber 18 at the outlets of the passages 17 and 20, assuring that all of the mixed contents are flushed out of the chamber.

The invention provides an ingenious solution to an annoying problem and one which does not add noticeably to the cost of either the gun or its operation and permits continued use of present guns with only the provision of a new or modified mixing rotor.

Having described my invention, l now claim.

1. in a gun for mixing and discharging successive controlled amounts of a two-ingredient mixture of resin and a catalyst, which gun has a mixing chamber with a motor-driven mixing rotor, mounted for rotation therein and a discharge outlet coaxially of the rotor, the improvement comprising:

means on said rotor for exerting an axial flow impeller type effect on the mixture in the mixing chamber in a direction away from said outlet to increase turbulence in the mixture within the chamber,

and said means on said rotor comprising a plurality of wedge-shaped radial blades.

2. The improvement of claim I wherein:

the upstream face of at least one of said blades is inclined at an angle to the direction of flow of the mixture through the chamber and to the tangent to the circular path described by the rotating blade.

3. The improvement of claim 2 wherein:

said plurality of blades is fixed to the shaft of said rotor in a series of opposed pairs,

and alternate pairs of said blades are axially spaced aLong said shaft by a distance at least as great as their largest axial dimension.

4. The improvement of claim I wherein:

the upstream faces of said blades are substantially planar.

S. The improvement of claim 1 wherein:

at least one of said blades is located adjacent the discharge end of said chamber and closely spaced to the discharge outlet for said gun.

6. The improvement of claim 1 wherein:

at least one of said blades is located adjacent the discharge end of said chamber and is spaced an equal distance from said discharge end across its entire radial extent.

7. The improvement of claim 1 wherein:

the upstream faces of a plurality of blades are inclined at an angle to the direction of flow of the mixture through the chamber and to the tangent to the circular path described by the rotating blades,

and wherein the inclination of the upstream faces of said blades decreases as their respective distances from the outlet increases. 

1. In a gun for mixing and discharging successive controlled amounts of a two-ingredient mixture of resin and a catalyst, which gun has a mixing chamber with a motor-driven mixing rotor, mounted for rotation therein and a discharge outlet coaxially of the rotor, the improvement comprising: means on said rotor for exerting an axial flow impeller type effect on the mixture in the mixing chamber in a direction away from said outlet to increase turbulence in the mixture within the chamber, and said means on said rotor comprising a plurality of wedgeshaped radial blades.
 2. The improvement of claim 1 wherein: the upstream face of at least one of said blades is inclined at an angle to the direction of flow of the mixture through the chamber and to the tangenT to the circular path described by the rotating blade.
 3. The improvement of claim 2 wherein: said plurality of blades is fixed to the shaft of said rotor in a series of opposed pairs, and alternate pairs of said blades are axially spaced aLong said shaft by a distance at least as great as their largest axial dimension.
 4. The improvement of claim 1 wherein: the upstream faces of said blades are substantially planar.
 5. The improvement of claim 1 wherein: at least one of said blades is located adjacent the discharge end of said chamber and closely spaced to the discharge outlet for said gun.
 6. The improvement of claim 1 wherein: at least one of said blades is located adjacent the discharge end of said chamber and is spaced an equal distance from said discharge end across its entire radial extent.
 7. The improvement of claim 1 wherein: the upstream faces of a plurality of blades are inclined at an angle to the direction of flow of the mixture through the chamber and to the tangent to the circular path described by the rotating blades, and wherein the inclination of the upstream faces of said blades decreases as their respective distances from the outlet increases. 